Chosen answer:When the kid goes up to Marvin and talks to him, he says "Klingo Mach" or something. That means "you speak Klingon?" Then the kid says "Egchad" which means "yes". That thing with the hands means hello or goodbye depending when you use it.

When Ben gives Eddie Murphy the picture he drew of them, Eddie points out that Ben drew a green moustache on him in the picture, but when he looks at the drawing for the first time and also in the meeting there's no moustache.